Politically, John Pym was very important until his death in 1643. He kept Parliament’s war effort together and his leadership was vital to the Earl of Essex’s survival in the war. He made sure that all of Parliament were for defeating the King and the Royalist forces as the were members in Parliament, in the Peace Party that wanted negotiation with Charles but Pym was completely against this idea so convinced them to agree to fight the King. John Pym’s most important contribution to Parliament’s war effort was his negotiations with the Scots to send an army to fight for Parliament in the Solemn League and Covenant. The Scots wanted something in return, a religious conformity with the Presbyterian Church in Scotland but Pym agreed to this as he did not expect to carry out this part of the agreement anyway as he knew that this sort of settlement would be hugely unpopular. The Scottish made a useful contribution to Parliament’s war effort, they invaded the Royalist areas in the north and sieged Newcastle and York and helped Parliament win the Battle of Marston Moor.
Even though they had won at Marston Moor and gained the majority of the north of England, many supporters and members of Parliament were unhappy and impatient with many of the generals in the Parliamentary armies. This led to a change which started with the Self Denying Ordinance. The ordinance aimed to get rid of the political and aristocratic generals such as the Earl of Essex who had humiliated himself at Lostwithiel and afterwards lost thousands of men and replace them with proper military commanders. Another solution to their issues was the creation of the New Model Army in early 1645. This was a professional army consisting of around 22,000 soldiers which was paid regularly and highly trained and according to the historian Angela Anderson, this creation was a ‘Military Revolution’ as an army like this had never been seen before and brought Parlaiment huge success. All this change showed Parliament’s determination to finish the war as quickly as possible as without the changes Charles still had a reasonable chance of winning the war despite his significant loss at Marston Moor.
There were many military reasons why Parliament won the first civil war. After their changes in early 1645, they had good, strong commanders such as the Lord General of the New Model Army, Sir Thomas Fairfax who was a capable and respected commander and Oliver Cromwell who was highly successful cavalry commander who surprised people by recruiting on the merit of a soldier and not the rank of one like others. Another vital military factor in Parliament’s victory was their control of the navy which allowed them to block off and stop any Royalist attempts of getting foreign military support from allies such as Charles’ wife Henrietta Maria who was in France at the time. Parliament’s decisive victory at Naseby effectively won the civil war for them as they had wiped out the main part of the Royalist army and the Royalists could never recover from this defeat.
The failures of Charles I and the Royalist Army was another reason for the outcome of the civil war as Charles had made fatal errors and poor decisions in the war even when they had the early advantages. An example of Charles’ poor leadership was after the stalemate at Edgehill, Charles had the perfect opportunity to march on London and attempt to capture it, instead he ignored the opportunity and just settled to march slowly back up the Thames to Oxford, he had missed what could have been a perfect opportunity for him to get a huge advantage in the war. He also demonstrated inadequate leadership skills before the Battle of Naseby where despite not been ready and advised by Prince Rupert not to, he decided to take on the New Model Army which had disastrous consequences for him and the Royalist war effort as after this defeat, he had effectively lost the war as the surrender of Bristol and Oxford and Charles’ surrender to the Scots followed.
There were many important reasons for Parliament’s victory in the first English Civil War such as their much better financial position, superior resources and the control of the navy but it was their annoyance and impatience with the Parliamentary army in 1644 which led to the Self Denying Ordinance and the creation of the New Model Army that was the most important reason. After these two events happened, Parliament became much stronger with 22,000 professional soldiers and were now no match for Royalist’ much weaker, amateur army and the war was over in a little over a year after these vital changes to Parliament’s forces.